Actuators and their associated servo control loops are used in a variety of different applications. As these applications continue to become more sophisticated, there is a desire to increase the performance characteristics of the actuators.
For example, data storage systems have tended to be made ever smaller, yet with ever greater storage capacity, as technology has advanced. Such data storage systems are usefully applied in a wide variety of settings including computers, networks, digital music players, PDAs, digital still cameras and video cameras, and external computer memory, among a wide variety of other possible examples. In one illustrative data storage system, for example, data is written onto and read from a medium by a transducer mounted on a slider. The slider is suspended from a suspension coupled to an actuator arm that is rotatably mounted on a base and driven by a voice coil motor. The actuator arm positions the transducer relative to a data track on the medium, responsively to a seek command.
There remains a persistent need for providing actuators in data storage systems and other applications with increasingly superior performance characteristics, including by reducing size, raising storage capacity per unit of size, and raising the speed with which the actuator operates. One limit on the performance of a data storage system is the accuracy with which the system can evaluate and control the position of the read/write head or other form of transducer to the positions of data within the system. The better performance characteristics of data storage systems have involved an ever shrinking gap between adjacent data tracks on a storage medium, and ever increasing servo open loop bandwidth for controlling the position of a read/write head relative to the data tracks. One impediment to further improvements in data storage system performance is the mechanical vibrations caused by the servo-controlled actuator arm as it is rotated to position the transducer to desired positions. Testing has shown such seek-induced vibrations to be a major factor limiting the performance of data storage systems.
One or more embodiments of the present disclosure provide solutions to these and other problems, and offer other advantages over the prior art.